Don't worry about that - join. I need some tail enders to learn my way around with. Find myself about four or five seconds off the pace on some tracks and I haven't been kicked - so go for it. (be quick though 'cause I was doing 1.10.xx on AS Nat this morning - only 3 secs behind... )
One thing I have found is that on my arthritic laptop (800 x 600, no AA/AF, 30fps with a clear road, YEAH!!!) is that the TBO cars seem to be more graphic intensive than the XRG/XFG/UF1. I can be finding my way through an 11fps slide show at T1.... The LODs seem to more forgiving (more drastic) with the slower cars. Is this right?